Actiontec GT704-WG. Qwest DSL used to require you to have an Actiontec GT701-WG, which has a DSL modem, a 100 Mb/s Ethernet port, USB, and 802.11b/g. I managed to fry mine with a sloppy firmware upgrade, and bought the 704 at Best Buy to replace it, with the assurance that it would be well-supported, since it's almost the same thing. Unfortunately, they're both junk. Neither Qwest nor Actiontec provides firmware updates, and their feature sets are somewhat limiting. There aren't any open source firmwares for them, like Tomato or DD-WRT.
Windows Media Center on an old Dell 400SC. This was marketed as an entry-level server, but really it's just a desktop PC like any other. I've added a WiFi-N card.
Windows Home Server on an old Dell D600. This is a laptop, which seemed like a great idea for a WHS. I love that it has a built-in keyboard, monitor, mouse, WiFi, and battery backup. Unfortunately it only supports IDE drives, so I'm limited to 250GB, and they're expensive. When I ran out of storage, I added an external drive, and eventually replaced that enclosure with:
A 2-bay external SATA enclosure. This contains a 1TB drive and a 300GB drive.
Also: A desktop with a Wifi-N card, a D600 (used as a laptop, gasp!) with 802.11g, and a new Lenovo T61, with WiFi-N builtin (sweet, sweet laptop).
Constraints: The only phone line is in the kitchen, which isn't a good place for electronics. The video collection lives on the server, but is played on the media center, and 802.11g isn't fast enough for DVD playback. Pushing data between the desktop and the server over WiFi was really, really slow. The WiFi in the Actiontec unit is really bad at doing in- and out-going traffic at the same time.
- server sits right next to the media center, with an ethernet cable between them. It doesn't need to be a crossover, because everything is autosensing these days. It doesn't have any DHCP; both devices complain that there's "limited connectivity", but they can still see each other just fine.
- A long phone cord runs over the door from the kitchen to the main desk. It plugs in to the Actiontec, which has Ethernet to the desktop (making desktop<->server links much faster).